The invention relates to a nodular cast iron alloy for cast iron products with plastic deformability, the nodular cast iron alloy containing, as non-ferrous constituents, at least the elements C, Si, Mn, Cu, Mg, S and, as admixtures, one or more elements selected from group IIIb of the periodic system (IUPAC form).
In the automotive sector, nodular cast iron alloys are used for the production of castings which have to be able to withstand a high impact load, for example wishbones, as parts of the suspension of the driven wheels which have to remain intact even after an accident. During what is known as the crash test, the castings may be deformed but must not break. Commercially available grey cast iron alloys tend to fracture if they are exposed to strong impacts.
WO 99 45 156 A1 has disclosed a process for producing nodular cast iron alloys with product inclusions which are deformed plastically during the machining of the products which are produced. The plastically deformable inclusions serve as lubricant during the machining. The inclusions consist of approximately 50% by wt. of SiO2, 25% by wt. of CaO, 15% by wt. of go and 10% by wt. of Al2O3. The base alloy is made to have a low sulphur and oxygen content prior to the actual treatment with magnesium, by means of a reagent which includes CaC2, CaO, Ca, Al and Mg. A metallurgical analysis of the products produced in this way is not disclosed.
Working on the basis of the prior art, it is an object of the invention to provide a nodular cast iron alloy for cast iron products with plastic deformability which is significantly higher than that of commercially available nodular cast iron alloys even in the event of a high impact load.